Extension valve-gear.



No. 733,157. PATENTED JULY 7,1903. E. P. COLEMAN.

EXTENSION VALVE GEAR.

APPLICATION TILED JULY 5. 1902.

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PATENTED JULY 7, 1903.

E. P. COLEMAN.

EXTENSION VALVE GEAR.

APPLICATION FILED JULY 5, 1902.

2 SHEETS-SHEET 2.

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IIINI 1 UNITED STATES Patented July 7, 1903.

PATENT ()FFioE.

EDGAR P. COLEMAN, OF CHICAGO, ILLINOIS.

EXTENSION VALVE-G EAR.

SPECIFICATION forming part of Letters Patent N 0. 733,157, dated July '7, 1903.

Application filed July 5; 1902. Serial No. 114,404:- (No model.)

1'0 (all whom, it may concern:

Be it known that I, EDGAR P. COLEMAN, a citizen of the United States, residing at Chicago, Cook county, Illinois, have invented certain new and useful Improvements in Extension ValveGears, of which the following is a specification.

This invention relates to extension valvegears for steam-engines, and has particular reference to extension-gears for Corliss engines.

There are many uses for steam-engines which may be described as emergency uses, the conditions being such that the engine is idle much of the time or, while normally carrying a small load, is occasionally required to drive an exceptionally heavy load. The practice has been in such cases to provide engines of a capacity equal to the largest load demands, which has entailed very large outlays in proportion to the sum total of work performed when compared with the cost of engines carrying a substantially unvarying load. The extended gear is especially useful on the low-pressure cylinders of compound engines, the long range of cut-off thus obtained enabling the operator to properly distribute the work between the high and low pressure cylinders at all times. This becomes doubly important with independent compound engines having separate independent crank-shafts for high and low pressure cylinders. Under the above conditions it has been found economical to employ engines having a valve motion that will enable the cut-off to be regulated from zero to maximumthat is, a valve-gearing that will supply the engine with steam throughout its full stroke when this is made necessary by a large load being thrown onto the engine. The Corliss engine being usually limited to a maximum cutoff of substantially forty-five per cent.that is, less than half-piston stroke-though economical in steam consumption, does not adapt itself to emergency uses and its valvegearing is of too limited range of cut-off for the low-pressure cylinders of compound engines. This has led to the use of the extension valve-gear for the Corliss engine, the object thereof being to retard the closing of the steam-valves and, if made necessary by the load, permit the engine to work under full stroke of steam. My invention is of this class and is designed to overcome the objections to the extension valve-gears hitherto employed, all of which have been criticized for complexity and lack of precision in operation. I find that these objections arise because of the adherence by designers to the old type of steam-hook, the arm of which travels around the valve-axis at a considerable distance therefrom, such constructions entailing complicated arrangements of the knock-off cams and other parts.

The particular object of this invention is to provide an extension valve-gear for Corliss engines in which the knock-off cams shall travel in spaces determined by a suitable regulator and shall alone be relied upon for releasing the steam-latches from the valvearms of the hook or trip levers, the valvecranks being relieved from other than passive duty.

A further particular object of theinvention is to greatly simplify the construction and lessen the cost of applying extension valve gears to Corliss engines.

My invention consists, generally speaking, in an extension valve-gear comprising the usual valve-arm, steam-latch, valve-crank lever, and knock-off cam-lever in combina tion with a trip-lever, the free end of which is substantially concentric with the axis of the valve, a knock-off cam pivoted at a point remote from the valve-axes, means for swinging the pivot-point about the valve-axis to change the stroke position of the knock-off cam, and means for regularly swinging or operating said knock-0E cam to operate the latch and free the valve-arm and valve.

My invention also consists in various constructions and in'combination of parts, all as hereinafter described, and particularly pointed out in the claims.

My invention Will be more readily understood by reference to the accompanying drawings, forming a part of this specification, and in which Figure 1 illustrates an extension valve-gear embodying my invention. Fig. 2 is an enlarged view of the valve-gear for one valve, and Fig. 3 is a sectional view thereof on the line to 5001": Fig. 2.

In the drawings I have illustrated the invention as applied to a Corliss engine of the prdinary horizontal type, but my invention s applicable to other types as well. The cylinder 2 has the usual inlet or steam valves and exhaust-valves, and 22 represents a suitable valve-operating slide or part that is worked from an eccentric on the engine crankshaft. The exhaust-valves need not be described, the invention being shown in connection with the inlet or live-steam valves. The valve -gears are identical for the two valves except as to positions, which are reversed, and the invention will be better understood by considering a single valve. The double valve-arm at, the dash-pot, the rod 4, the steam-latch 6, the valve-crank 5, the reach-rod 23 therefor, and the knock-oi? catnlever 10 are of the ordinary design. The valve-arm 4 is fixed upon the valve stem 3, (see Fig. 3,) while the latch 6 is pivoted upon the lever 5, which is journaled upon the valvestem 3. The lever 5 is provided with a boss, on which the knock-cit cam-lever 10 is journaled. The latch 6 is spring-pressed, as usual, but differs from like parts of other engines in having alonger trip-lever 7,whieh instead of approaching astationary knockoff toe at a tangent thereto occupies a radial position,with its free end 8 substantially concentric with the valve-stern, this being the position when the latch is still engaged with the valvearm at. The lever 5 is worked regularly by the slide 22, and the latch engages the Valve arm and is released therefrom during the repective strokes of the slide on the engine-piston, the slide operating substantially ninety degrees plus lead in advance of the piston. The knock-off cam-lever 10 is provided with an outboard bearing 11, which, extending inwardly, encircles a boss on the valve-arm 4, that serves as a journal therefor. On this outboard bearing is a stud 12, upon which the knock-oif camarm 13 is journaled, said arm having a camsnrface 14, adapted to engage and operate the free end of the trip lever, and thus throw out the latch to release the valve-arm 4. The knock-off cam-lever 10 remains stationary during the operation of the engine under constant load, but is moved when the load of the engine changes.

Referring now to Fig. 1 of the drawings, it

- will be seen that the two knock-E cam-levers are connected by the rod 17 and the T 18, which is journaled on the fixed stud 19. The T 18 is adjustable by means of the screw-spindle 20 and the hand-wheel 21, or in place of this hand-regulating means the T may be connected directly to the engine-governor. In most instances where the use is of off cam-arms.

phase relation to the slide-rod 22 and connected parts. The knock-01f cam-arms 13 being on the levers 10 at points remote from the va'lve-cen ters and having their free ends held by the rod 15,it will be evident that when the levers 10 are moved by means of the regulator the positions of the pivots or studs 12 will lease of the valve-arm will be hastened or retarded to decrease or increase the period of steam admission to the cylinder. The stroke of the knock-off cams may be so far retarded with relation to the trip-levers that steam will be admitted during substantially the entire stroke of the engine-piston, the knockofi' movement occurring during the closing movement of the valve-arm 4 at each valve, an operation that is impossible with the ordinary Corliss valve-gear.

The advantages of my extension valve-gear are simplicity of construction, firmness of bearing for the knock-01f cams, and precision of operation of the knock-01f cams and steamhooks, and the ease with which the single eccentric Corliss gear may be converted into an engine with extended releasing-gear. It is obvious that the hand or governor regulator may be connected between the knock-off cams and the regular movement imparted to the knockoff cam levers l0 and generally that various modifications of my invention will readily suggest themselves to one skilled in the art, and I therefore do not confine my invention to the specific construction herein shown and described.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. An extension valve-gear comprising the usual valve-arm, latch, valve-crank and knock-oi? cam-lever in combination with a trip-lever the free end of which is substantially concentric with the axis of the valve, a knock-off cam pivoted at a point remote from the valve-axis, means for swinging the pivot-point about the valve-axis to change the stroke position of the knock-0E cam and means for regularly swinging or operating said knock-off cam to operate the latch and release the valve-arm and valve, substantially as described.

2. The extension valve-gear comprising the ordinary Corliss valve-gear in combination with radial trip-levers, knock-off cams pivoted at points remote from respective valveaxes, means for operating said cams and means for swinging the pivots of said cams about their respective valve-axes, substantially as described.

3. The extension valve-gear comprising the valve-arms, latches and valve-cranks of the two valves and means for operating the same, in combination with the trip-levers, knockoff cam-levers suitably connected and the regularlymoving knock-off cams arranged on said knock-off cam-levers, substantially as described.

at. The extension valve-gear comprising the valve-arms, latches and valve-cranks of the two valves and means for operating the same, in combination with the trip-levers, knockoff cam-levers suitably connected and the regularly-moving knock-oft cams pivoted on said knock-off cam-levers and adjustable thereby and operating means connecting the knock-01f cams of the two valves, substantially as described.

5. In an extension valve-gear for Corliss engine, the combination of the valve-arms, latches and valve-cranks with the trip-levers having their free ends substantially concentric with the valve-centers, the knock-off cam-levers, a regulator or governor connection between said knock-off cam-levers, the knock-off cams pivoted upon said levers and means connecting said knock-off cams for operating the same in proper time with the valve-cranks, substantially as described.

6. In an extension valve-gear for a Corliss engine, the combination, of the steam-valves, the valve-arms thereof, the latches, the valvecranks and operating means, with the triplevers, the knock-off cam-levers, means for adjusting said knock-off cam-levers, the knock-off cam-arms pivoted on said knockoff. cam-levers and having cam -surfaces to engage respective trip-levers, means connect ing the knock-off cam-arms and means for regularly operating said cam-arms and cams, substantially as described.

7. In an extension valve-gear, the combination of the valve-arms, latches and valvecranks regularly operated, with the trip-levers, the knock-off cam-levers situated behind the valve-arms and having the outboard bearings described, the knock-0E cams pivoted on said outboard bearings to engage said trip-levers, means for operating said knockoff cams regularly and means for adjusting said knock-off cam-levers, substantially as described.

8. In an extension valve-gear for Corliss engine, the combination of the valve-arms, of the valves, with the latches and valve-cranks therefor, the valve-crank-operating means,

the trip-levers 7 having their free ends substantially concentric with the valve-centers, the knock-0E cam-levers 1O concentric with the valve centers, the outboard bearings thereof, the knock-off cam-arms 13 pivoted on said bearings and having cam-surfaces 14 to engage said trip-levers 7, rigid means.15 connecting said knock-off cam-arms, means for operating the same and the regulator connection between the said levers 10, substantially as described.

9. The extension valve-gear comprising the usual Corliss valve-gear, in combination with radial trip-levers for the latches of said gear, knock-off devices pivoted at points remote from respective valve-axes, means for shifting the pivot-points of said devices and regular operating means for actuating said devices to meet said trip-levers, substantially as described.

10. The extension Valve-gear comprising the usual Corliss valve-gear, in combination with radial trip-levers for the latches of said- Corliss gear, knock-off cam-levers, knock-off devices carried thereby and adjustable therewith about the valve and means for operating said levers and said devices, substantially as described.

11. The extension valve-gear comprising the usual valve-arms, latches, valve-cranks and operating means, in combination With the trip-levers for said latches, the free ends of said trip-levers being, normally, substantially concentric with the axes of said valve, the knock-off cam-levers suitably pivoted concentrically with said valves, means for adjusting the same, the knock-off devices arranged upon said cam-levers and adjustable thereby and means for regularly operating said devices, substantially as described.

12. An extension valve-gear comprising the usual valve-arms, latches and means for operating the same, in combination with the radially-disposed trip-levers of said latches, the knock-oft cam-levers pivoted concentrically with respect to the valves, means for adjusting said levers simultaneously, the outboard bearings upon said knock-off cam-levers, the knock-off devices arranged thereon and the regularly operative means for actuating said devices, substantially as described.

In testimony whereof I have hereunto set my hand, in the presence of two witnesses, this 14th day of June, 1902.

EDGAR P. COLEMAN.

In presence of- C. G. HAWLEY, J. W. BEOKSTROM. 

